HDR

HDR / HDRI

PanoramaPalace Rui Pedro

The HDR (High-dynamic-range imaging) is a photography technique which makes it more capture “range of light” in the image.

 It has happened to all of us shooting that way to the beach and the sky is white or, in the middle of the woods, shooting the treetops and branches turn black.

 What is happening is that the “amplitude” of the sensors still fail to capture everything that the human eye can see, and if the scene has a lot of range of light is normal to be anything “burned” / under exposed.

 With the HDR we can expand this range to any value. You can have the sun in front and a shadow to a basement, in the same picture, and get a blue sky and see the details in the basement.

 The HDR is usually composed of multiple exposures and can be done automatically (AEB – auto exposure bracketing) or manual (by varying the exposure times of something “fast” for the blue sky to something slow to get the detail of the basement , for example). It is possible to build a HDR image from only one RAW image

Note: AEB serves to more things than creating HDR images.

To make a manual Exposure Bracketing is highly recommended using a tripod since it involves removing the framework of the machine, look, fit, replace the machine in the environment and this will cause a misalignment of the images. In the case of the AEB, although also the tripod is advisable, depending on the focal length, can be handheld and the software used will re-align the pictures.

There are many software to join multiple pictures and build HDR images. Photoshop of course, photomatix, oloneo, nik hdr, hdr MediaChance, etc. Try it and enjoy the results.

Usually what I do (because I like to HDR’s that result in normal pictures) is to get an image in TIF 32bit and then use Adobe Lightroom for … whatever I want. The resulting images are “bullet proof” in the sense that, being too dark or too light never “burn” in white or “lose detail” in the shadows.

AEB – Auto Exposure Bracketing

PanoramaPalace Rui Pedro

AEB – Auto Exposure Bracketing is a functionality present in photographic cameras for many years. This feature makes N exposures with the “distance” to the middle of EV’s preconfigured. This distance can be of exposure value, apperture or with digital cameras, ISO.

Many years ago, while using film cameras, I received a mail with some thoughts on photography and one of which was “Use bracket. Film is cheaper than a new trip. “If the roll time it was advised, imagine the digital time! Memory card is much cheaper than a new journey.

Bracketing idea is to prevent photo exposure errors caused by automatic or manual settings.

If, for example, the amplitude of the image is 14 EV’s (-7 to +7), depending on the scene, we can bracket [-2.0 + 2], ie, from -9 to +5 (getting good exposure for lights sun and sky blue), -7 to +7 (normal exposure) to +9 -5 (good exposure in shadows) regarding automatic settings or M mode.

At home, calmly, we look at the histogram and we select the photo that best corresponds to our idea for the scene. If we choose the darker able to regain some shadows but we have all the detail in the highlights. If we choose to have clearer detail in the shadows but possibly the Sun will be a larger ball. It is a matter of personal taste.

Depending on the situation it may be desirable that the driving mode – shooting mode is

  • – Burst. Takes 3 pictures then the maximum speed of the camera fps shooting. The N pictures are made quickly (at camera fps) and can be used in any subject in motion during the day.
  • – With timer. Can be with or without mirror / lockup in case it is essential that the machine does not shake (of course, a tripod). If the camera is mirrorless has no mirror lockup.

After shooting AEB we can always produce an HDR image stretching the amplitude of various light images to an image much “richer” in light amplitude.